1. Field of the Invention
The present invention relates to the field of photography and, more particularly to compact self-developing camras.
2. Description of the Prior Art
The terms -- compact, pocket size, miniature, or subminiature -- as used in this disclosure in connection with self-developing cameras are descriptive of the relatively small physical size of both the cameras and the small format self-developing film units used therein. Small format means that such film units have image forming areas more closely approximating a 35 mm frame than the much larger "snap-shot size" frame.
There are a number of compact or pocket size cameras presently on the market that use conventional (not self-developing) 35 mm or 110 form film. Characteristically, these cameras are small in size and wieght, highly automated in terms of exposure control and are generally rugged in construction.
Generally, the 110 format cameras have such a small lens to film plane distance that the objective lens is mounted on a fixed lens board which does not have to be retracted into the housing for storage. On the other hand, some 35 mm cameras are of the "folding" type which include a lens board and bellows assembly which is movable between extended and retracted positions.
In order to eliminate the need for a separate carrying case to protect the camera optics and/or other externally mounted and rather delicate mechanisms, some of these cameras have self-contained telescoping or expansible camera housings or bodies which expose or uncover the optics and/or mechanisms when extended and form a protective casing over these structures when they are closed or retracted.
For representative examples of such conventional pocket size cameras having full or partial covering protective expansible housings reference may be had to U.S. Pat. Nos. 3,680,455; 3,864,705; 3,950,771; and 3,987,469.
The above-noted pocket cameras are not self-developing cameras. In addition to the optics, they include automatic exposure control devices and a film advance mechanism that is subject to rather light loading in operation.
A major problem area in providing a pocket size self-developing camera is that in addition to the optics and automatic exposure control devices it also must include a pressure-applying mechanism, such as a pair of rollers, for processing the film unit after exposure, a relatively heavy duty film transport system for advancing an exposed film unit through the pressure rollers and, if the film unit is of the type which does not include a self-contained total light opacification system, a light excluding imbibition chamber in which the film unit is held for a short time following pressure application to prevent fogging while the development and diffusion transfer process is in progress.
Most of the compact or smaller size self-developing cameras known in the prior art are designed for use with "instant slides", i.e. full color transparency film. In general, these film units do not include a complete self-contained post pressure-applying light-shielding system and must be held for the short imbibition period in a camera mounted imbibition chamber.
For representative examples of the prior art relating to compact instant slide cameras, reference may be had to U.S. Pat. Nos. 2,854,903; 3,225,670; 3,350,990; 3,369,469; 3,369,470; 3,421,423; 3,437,023; 3,437,024; 3,446,127; 3,446,131; 3,455,222; 3,525,293; 3,541,937; 3,541,938; 3,541,939; 3,541,940; 3,575,081; 3,614,920; 3,636,844; and 3,648,527. Also see the copending application of J. J. Driscoll, et al, Ser. No. 749,511, filed Dec. 10, 1976 and assigned to the same assignee as the present application.
The addition of the imbibition chamber in alignment with the rollers creates the problem of increasing camera size. While some of the above-noted instant slide cameras have fixed chambers, some cameras make use of a folding or self-storing chamber so that the camera approaches pocket size at least in the inoperative position. For examples of other self-developing cameras with folding or expansible imbibition chambers see U.S. Pat. Nos. 2,467,320; 3,618,493; 3,650,188; 3,653,308; 3,702,580; 3,748,990; and 3,852,781.
It is also well known in the art to provide self-developing cameras which achieve compactness by providing folding or expansible and retractable housing sections and to include as part of the housing sections portions thereof that serve to protect, when folded or closed, the camera optics and/or other delicate mechanisms. Representative examples of such prior art may be found in U.S. Pat. Nos. 2,590,164; 2,880,658; 2,930,301; 3,194,137; 3,677,160; 3,691,920; 3,706,267; 3,737,315; 3,810,211; 3,680,445; 3,864,705; and 3,950,771.
All of the above-noted self-developing cameras in this section have at least one major drawback. Some cameras do not even come close to approaching true pocket size. Others do not include imbibition chambers and thus cannot be used to process self-developing transparency film units that do not have self-contained total light opacification systems. Still others do not include a self-contained protective casing for the optics and require the use of a separate carrying case for protection against damage. Some of those cameras that do approach pocket size tend to have a thin elongated shape and are not necessarily easily stored and retained in a shirt pocket. Also, some pocket cameras achieve small physical size by using 110 format film (13 mm .times. 17 mm frame) which inherently limits the size of an image that can be projected onto a viewing screen or limits quality prints to snap shot size photos.